The present invention relates to a carpenter's level and in particular to a carpenter's level that may be extended.
It is well known in the art that there have been a wide variety of levels offering extension capabilities. Starting from the typical situation that one frequently sees in the field, the carpenter may obtain several straight studs and assemble an extension level at the site. Once all of the appropriate elements of an extension level have been assembled for the initial application, the user will of course attempt to keep all of the pieces together, store them, and maintain them for future use. This presents some difficulty in view of the fact that the sizes of the various pieces may be quite large, the pieces are generally separate, and not fabricated as a system so that some of the pieces may become lost if not carefully stored, and because of the specific and custom nature of the original assembly for the particular application the pieces may not be easily rearranged when reassembled to immediately satisfy the new application. Likewise with the multitude of extension levels that are known in the art some of these same problems have existed. Thus, the sizes of some of the extension levels are not large enough to address the types of applications that the present invention addresses and the sizes of the elements of some of the extension levels known in the art are such that they are inconvenient to carry and store. This latter issue is specifically of concern when one realizes that frequently these devices are carried in the trunk of a car, or utility tool boxes in pickup trucks which will not accommodate lengths over five and one half feet.
A number of examples of extension levels to which reference may be made for information relating to applications and solutions considered in the past are reflected in the following patents which the applicant hereby incorporates by reference herein: 4,607,437; 4,130,943; 3,811,197; 3,648,378; 3,104,477; 3,161,964; 2,879,606; 2,419,451; 1,430,904; 1,413,056; 1,403,676; 945,275; 747,850; 686,360. These patents address a variety of applications that various people have considered, and they show the spectrum of devices that have been created to address some of the solutions either in whole or in part. One can see that in this spectrum there are some extension levels that are more complicated than others, and that a number of these levels are somewhat complicated to fabricate and manufacture. The issue of wear and performance variations due to wear do not appear to have been addressed. Thus, in addition to the size of the extension levels that have been devised, the reliability in providing the desired plumbing and trueing capabilities for an extension level to be used in a particular application, and the producibility and cost of manufacturing many of these devices has varied considerably.
It is thus an object of the present invention to provide an accurate means for checking plumb and level over a range from the length of a standard three foot level to lengths for setting standard door jambs and plumbing walls, respectively. Thus, it is intended to provide a device that can be varied from the standard three foot length to at least the additional lengths of six foot six inches for door jambs, and eight foot for plumbing walls.
It is another object of the present invention to provide an extension level with the structural rigidity demanded for maintaining accuracy over the entire adjustment range and over an extended period of use and life expectancy.
It is yet another object of the present invention to provide a rigid means of holding the plumb and level bubble vials within the extension level structure.
It is another object of the present invention to provide for slidable adjustment for an extension level with a minimum of structural resistance and wear.
Another object of the present invention is to provide an extension level functionally capable of spanning warped surfaces between its extremities.
Yet another object of the present invention is to provide an extension level adaptable for applications involving metal studs and construction members as well as wood and other construction material.
Still another object of the present invention is to provide an extension level that is easily collapsable for storage, handling, and transport.
Finally, it is an object of the present invention to provide a positive locking of the extension elements of an extension level to the base level at preselected or custom lengths.
The present invention addresses all of the above demands for an acceptable extension level by means of three basic structural members, specifically including a base level of the standard three foot size which contains the bubble vials within apertures or viewing ports, and two sleeve-like extension which slide over and are held securely to the base level at points appropriate to provide an overall extension level capable of handling the six foot six inch application demands and the eight foot requirements for such a level. Applications requiring level lengths other than six feet six inch and eight feet can be addressed by drilling a seven-sixteenth inch diameter hole in each extension in line with and spaced from the depress button holes already in existence. All of the functional elements required to permit these three major structural elements to perform their job are part of these elements with the exception of two spacer blocks which are slidably secured to the extremities of the two extension sleeves which slide upon the base level. The spacer blocks are only secured to the extensions when needed for applications where spanning irregular surface features of the structural member being checked is a requirement.